The extraordinary billowing sail of the Burj al Arab, and the construction of the world's tallest building, the Burj Dubai, catch the eye of even long-time residents. There are few countries with structures that match those in the UAE. However, in Australia and Africa there are towers that arguably are more impressive, even though they stand only a few metres off the ground. If termite mounds were scaled to human dimensions, they would stretch more than a mile into the sky, well over twice the height of the Burj Dubai.
Ranging in shape from domes to cones, mounds and towers, these colonies, some as tall as nine metres and housing as many as two million termites, have much to teach designers creating the cutting-edge structures. In particular, designers hope to create buildings that are more capable of circulating air and regulating temperature while using much lower levels of energy. A team of engineers, entomologists and physiologists led by Dr Rupert Soar from Loughborough University in England has been studying termite mounds in Namibia for the past five years.
"They are more equivalent to a cityscape with many skyscrapers than to an individual building," says Dr Soar, whose team also includes scientists from the University of Cambridge and the State University of New York. The researchers, by creating gypsum moulds and digitally scanning the structure of the mounds, have discovered a remarkable ventilation system that circulates air through the use of a resonance effect. This system, Dr Soar believes, could create major changes in the way buildings are designed and constructed.
The process has many parallels to the way people breathe. While with lungs, air is moved in and out through the action of muscles, the termites harness wind energy to drive gaseous exchange. "The termite mounds achieve very high levels of exchange of respiratory gases without bulk exchanges of air," Dr Soar says. "It draws in oxygen and draws out carbon dioxide as effectively as if you or I were breathing.
"They do it by building structures that resonate or hum, using a natural frequency. The implications for buildings are enormous." Air is moved using a system of thousands of channels built by the termites (Macrotermes michaelseni) in the walls of the mounds, similar to the capillaries of human skin. These "egress channels", which loop and link up with one another, create a sloshing air movement - like an alternating electric current - that in turn creates a resonant effect within the air column inside the termite mound.
While conditions outside can fluctuate dramatically, inside the termite mounds temperature, moisture content and levels of gases such as carbon dioxide and oxygen must remain much more constant. Maintaining these optimum conditions is vital for the survival of a fungus that termites farm inside the mound. The fungus is essential for termites to break down the chewed wood fibre. "It is very difficult for most physicists and biologists to understand the system," Dr Soar says.
"We struggle to understand transient systems that change all the time. We try to break things down into steady flows." In particular, Dr Soar says architects tend to think in terms of stack effects - the way a chimney draws up air. The stack effect has been used by many architects, among them Mick Pearce, who designed the Eastgate, a tower in the Zimbabwean capital, Harare. Air is drawn in from the atrium by fans and circulated to upper storeys using spaces under the floor. Warmer air is drawn out by ceiling vents and eventually exits via chimney stacks in the roof. Dr Soar describes this system, which vastly reduces the building's energy use, as "80 per cent there".
"With a termite mound, there are no holes at the bottom, but the architect will assume there are. There are so many misconceptions," he says. Deep within the mounds, another sloshing effect is created. This exchanges gases in a manner similar to that at the alveoli, the tiny extremities of the human lungs. "You get a full bronchial system taking place within a termite mound, which is a pile of earth," he says.
Taking lessons from the termite mound, Dr Soar believes people should try to create buildings with walls that are permeable and allow an oscillating air flow. Instead of being barriers to air flow, walls should be membranes. This, apart from saving energy by creating a more natural air flow instead of one powered by electricity, would help to eliminate problems such as dampness that result from having buildings that are almost air tight.
"Buildings are designed as hermetic boxes," Dr Soar says. "We create barriers with the environment with walls. With this research, we are trying to change this and turn it on its head. That's the fundamental change we need to bring to construction." This would require new building methods known as free-form construction, based on the techniques of rapid prototyping, which involves building up three-dimensional structures using machines that deposit one layer of material at a time.
To understand this, Dr Soar makes a comparison with an inkjet printer that, were it not printing on paper, would create a build-up of ink of a particular shape. "We don't use ink - we squirt concrete or gypsum and we print the whole building that way," he explains. "When you're printing something, the printer doesn't care if it's a complex line or a straight line, but a bricklayer does." As a result, traditional bricks and mortar are out, as they are unable to create the complex, breathable structures.
At the moment, the most obvious way in which Dr Soar's research could be used in construction would be through the printing and fabrication of panels that could be attached to buildings in order to achieve ventilation. Currently, his group is involved in a project involving the National Museum in the Namibian capital, Windhoek, with the aim that panels will be installed by 2010. "There would be a fundamental shift in the way buildings are conceived and produced," Dr Soar says.
dbardsley@thenational.ae
